Question

The charge flowing through the cell on closing the key $k$ is equal to

• A. $\frac{CV}{4}$
• B. 4 C V
• C. $\frac{4}{3}CV$
• D. $\frac{3}{4}CV$

Answer 1

Answer: (A)

When switch is open, the charge given to equivalent capacitor.
$q_i=\left(\frac{3C\times C}{3C+C}\right)\cdot V=\frac{3}{4}CV$
When switch is closed, $q_f=CV$
$\Delta q=q_f-q_i=CV-\frac{3}{4}CV=\frac{1}{4}CV$
Hence, charge passed through switch will be $\frac{1}{4}CV$.